This image shows a portion of Lethe Vallis, an outflow channel that also transported lava. The channel formed by catastrophic floods, during which it produced the prominent crater-cored, teardroped-shaped island in the middle. The island has the blunter end pointing upstream and the long tail pointing downstream. The margins of the channel also show the terminal front of a pristine lava flow unit that inundated the channel from the south and the dunes show the remnants of another older lava flow. The top of the island displays polygonal patterned ground texture, which is a characteristic of periglacial processes in ice-rich ground. Learn more about this image here.